CODEWITHSUNDEEP
matlaboop
user3089536
user3089536

Reputation: 21

How to update a property from within matlab class constructor

I'm new to object oriented programming in matlab and am having some trouble modifying some of my properties from within my class constructor. My class looks something like 

classdef kENot

properties
    Sys;

end   
 methods
        function obj=kENot(Sys)
            %Constructor
            obj.Sys=Sys;        
            obj.eyePrime

        end

       function obj=eyePrime(obj)
           obj.Sys.IPrime=5
       end

 end
end

Then from the comand line I call that constructor as 

Sys.Iprime=4;
classObj=kENot(Sys);
disp(classObj.Sys.Iprime)

And matlab prints 4. What I want is for the value of classObj.Sys.Iprime to update during the call to obj.eyePrime in t he constructor, but that doesn't see to be happening. Any thoughts?

Upvotes: 2

Views: 328

Answers (2)

sebastian
sebastian

Reputation: 9696

For completeness, making a handle class is not the only way to solve this.

As long as kENot is not a handle class, you'll always have to assign the output of methods that change the object to the variable holding the instance. In your current implementation eyePrime returns the modified obj. But you're not using the returned value.

So, you could change your constructor to:

function obj=kENot(Sys)
   %Constructor
   obj.Sys=Sys;        
   obj = obj.eyePrime();
end

Granted, this is pretty awkward syntax compared to all other object oriented programming languages and that's presumably why handle classes are favoured here.

As usual, there's pretty good documention from mathworks on this:

http://www.mathworks.de/de/help/matlab/matlab_oop/comparing-handle-and-value-classes.html

Upvotes: 2

Marcin
Marcin

Reputation: 238051

First I think that insead of obj.Sys.IPrime=5 you should have obj.Sys.Iprime=5, i.e. small 'p'. Second, I think you need to make handle class.

classdef kENot < handle
    properties
        Sys;

    end   
     methods
            function obj=kENot(Sys)
                %Constructor
                obj.Sys=Sys;        
                obj.eyePrime();
            end

           function obj = eyePrime(obj)         
               obj.Sys.Iprime=5;
           end

     end
end

Upvotes: 1

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